Test::AtRuntime lets you use Test::More and other Test::Builder based modules directly in your source code providing a way to test your program as it runs. Similar to the concept of an assertion, except instead of dying when it fails, normal "not ok" output will be seen.

Like assertions, they can be turned on or off as needed. Tests are put inside of a TEST block like so:

TEST { like( $totally, qr/rad/ ) }

use Test::AtRuntime runs these tests. no Test::AtRuntime means these tests will not be run. In fact, they will be completely removed from the program so that performance will not be effected (except some startup performance for the filtering).